Lake Mweru

Lake Mweru (also spelled Mwelu, Mwero) is a freshwater lake on the longest arm of Africa's second-longest river, the Congo. Located on the border between Zambia and Democratic Republic of the Congo, it makes up of the total length of the Congo, lying between its Luapula River (upstream) and Luvua River (downstream) segments. Mweru means 'lake' in a number of Bantu languages, so it is often referred to as just 'Mweru'. Mweru is mainly fed by the Luapula River, which comes in through swamps from the south, and the Kalungwishi River from the east. At its north end the lake is drained by the Luvua River, which flows in a northwesterly direction to join the Lualaba River and thence to the Congo. It is the second-largest lake in the Congo's drainage basin and is located west of the southern end of the largest, Lake Tanganyika. The Luapula forms a swampy delta almost as wide as the southern end of the lake. In a number of respects, the lower river and lake can be treated as one entity. For a lake in a region with pronounced wet and dry seasons, Mweru does not change much in level and area. The annual fluctuation in level is , with seasonal highs in May and lows in January. This is partly because the Luapula drains out of the Bangweulu Swamps and floodplain which tend to regulate the water flow, absorbing the annual flood and releasing it slowly, and partly because Mweru's outlet, the Luvua, drops quickly and flows swiftly, without vegetation to block it. A rise in Mweru is quickly offset by a faster flow down the Luvua. Mweru's average length is and its average width is , with its long axis oriented northeast–southwest. Its elevation is , quite a bit higher than Tanganyika (). It is a rift valley lake lying in the Lake Mweru-Luapula graben, which is a branch of the East African Rift. The western shore of the lake in DR Congo exhibits the steep escarpment typical of a rift valley lake, rising to the Kundelungu Mountains beyond, but the rift valley escarpment is less pronounced on the eastern shore.